[Mesa-users] Rotation in massive stars

[Silvana Vacchina]

Hi Simon,

Thank you very much for your answer.

If I try to rotate faster from the beginning, the MS is chaotic, it seems
that the star doesn't want to go to the red side and instead goes to
collapse in any strange way.

What I really don't know is if I'm using the proper parameters... If this
is the case then I accept that the increasing radius slows the star... is
just that I don't know why there are some massive stars which are fast
rotators, I don't know which parameters can give me that.
Maybe it's just a misunderstanding on my part, and I'm not understanding in
which exact phase or moment in the evolution you can get more rotation.

And I don't know which parameter can keep rotation rate fixed. Any more
tips regarding parameters would be really appreciated.


Thanks,

Silvana


El jue, 10 mar 2022 a las 23:00, Simon Murphy (<simon.murphy at sydney.edu.au>)
escribió:

> Hi Silvana,
>
> Rotation will slow down because the star's radius increases as it evolves
> on the main sequence. The star also gets a denser core as the mean
> molecular weight there increases. Conversation of angular momentum
> therefore suggests the surface should spin down but the core should spin
> up, unless you are using some physics to redistribute angular momentum
> throughout the star.
>
> Forgive me for asking, but why do you not want to evolve the star in this
> way, and to keep the rotation rate fixed, instead?
>
> If you are aiming to have v=300km/s at the TAMS, you might have to start
> your star rotating faster so that it has slowed to 300km/s at the TAMS.
>
> - Simon
> ------------------------------
> *From:* Mesa-users <mesa-users-bounces at lists.mesastar.org> on behalf of
> Silvana Vacchina via Mesa-users <mesa-users at lists.mesastar.org>
> *Sent:* 11 March 2022 02:00
> *To:* mesa-users <mesa-users at lists.mesastar.org>
> *Subject:* [Mesa-users] Rotation in massive stars
>
> Dear MESA users,
>
> I'm working on a project for a master degree and I would like to include
> rotation into my massive stars models, but I've realized that rotation slow
> down till one factor or less near the end of main sequence (MS) and never
> rises up again.  Rotation parameters are a bit complicated to me, and I'm
> not sure if I'm using them properly.
>
> I'm using r15140 and I've run several combinations of parameters without
> success, with a goal to keep a rotation v at around 300 km/s till He core
> burning, if that's possible.
>
> Could someone give me some tips on this? Am I missing a parameter maybe?
> Any help is appreciated.
>
> Thanks in advance,
> Silvana
>
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